| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery, in which the reduction of the discharge voltage at the initial period in the cryogenic temperature region can be restrained. SOLUTION: By using a particle substance of Li-Co series complex oxide satisfying equation [7<=20/(specific surface area × average particle size) <=9] as a positive electrode active substance, and further, by using a mixture of large-sized electrically conductive materials and small-sized electrically conductive materials as electrically conductive materials for positive electrode, which are combined in a positive electrode with the positive electrode active substance, a lithium ion secondary battery is made so that a discharge curve (horizontal axis: discharge capacity rate [%], vertical axis: discharge voltage [V]) which is obtained by 1C discharge in the environment of -20 deg.C has a downward curve toward the right side without the minimum value. |
